Method of Manufacturing Brake Disc and Brake Disc

Abstract

In a method of manufacturing a brake disc having an outer peripheral shape of projections-recesses repetition in which a radial projection and a radial recess are alternately repeated in the circumferential direction of the brake disc, there is provided a method in which a curved face portion can be formed uniformly over the entire outer peripheral edge portion of the disc main body so as to eliminate the step of chamfering for removing burrs and which is superior in productivity. A disc main body whose outer peripheral shape is projections-recesses repetition is half-blanked from one of plate thickness directions of a sheet material. Thereafter, the disc main body is blanked from the other of the plate thickness directions of the sheet material W. At an outer peripheral edge portion of each surface in said one and the other of the plate thickness directions of the disc main body manufactured by this method, there is formed a curved face portion, due to sagging, on the disc main body 1 in a manner to be in continuation of the sheared portions on an outer peripheral surface of the disc main body. The inner diameter R 11 of the die to be used in the half-blanking step is configured to be slightly smaller than the outer diameter R 12 of the punch.

1 . A method of manufacturing a brake disc having an outer peripheral shape of projections-recesses repetition in which a radial projection and a radial recess are alternately repeated m a circumferential direction of the brake disc, the method comprising:
 a half-blanking step of half-blanking a disc main body having the outer peripheral shape of projections-recesses repetition, the half-blanking being performed from one of plate thickness directions of a sheet material; and   a blanking step of blanking the disc main body from the other of the plate thickness directions of the sheet material.   
     
     
         2 . The method of manufacturing a brake disc according to  claim 1 , wherein an inner diameter of a die to be used in the half-blanking step is configured to be smaller than an outer diameter of a punch. 
     
     
         3 . A brake disc having an outer peripheral shape of projections-recesses repetition in which a radial projection and a radial recess are alternately repeated in a circumferential direction of the brake disc,
 wherein a disc main body having the outer peripheral shape of projections-recesses repetition is half-blanked from one of plate thickness directions of a sheet material and the disc main body is blanked from the other of the plate thickness directions of the sheet material such that a curved face portion is formed on the disc main body at an outer peripheral edge portion of each surface in said one and the other of the plate thickness directions of the sheet material, each of the curved face portions being in continuation of a sheared portion on an outer peripheral surface of the disc main body   
     
     
         4 . The brake disc according to  claim 3 , wherein a broken-out portion which is smaller in diameter than the sheared portions is formed on the outer peripheral surface of the disc main body in a manner to be positioned between the sheared portions in one and the other of the plate thickness directions.